Many types of roofing systems are used to cover a roof deck of a building. One type of roofing system is a prefabricated roofing system such as a metal roofing system. Typically, these metal roofing systems are formed from a plurality of metal panels. A number of prefabricated metal roofing systems have been developed. Such prefabricated metal roofing systems require substantial on-site construction and often do not make adequate provision for sealing around obstructions such as roof-mounted equipment and parapets. As a result, leakage can result at these points as thermal movement of the roofing system occurs. Furthermore, watertight integrity of such metal roofing systems is difficult to achieve and has led to various complicated and expensive systems such as roofing systems that use sealing membranes over the expanse of the roof surface. As a result, the roofing industry has long needed a prefabricated metal roofing system which can be quickly and easily erected with minimum labor and skill, which is reliably moisture-tight, and which is compatible with various building sizes, shapes and constructions.
One prefabricated type metal roofing system disclosed in U.S. Pat. No. 4,619,100, which is incorporated herein by reference, was developed to address many of these past problems associated with metal roofing systems. The '100 patent discloses an improved preformed roof structure in which a series of rectangular sheet metal panels are joined along adjacent longitudinal edges at a sealed interlocking joint to form an elongate sheet metal skin. The sheet metal skin is secured in place on supports on the roof decking. Adjacent longitudinally extending sections of the sheet metal skin are joined at an overlapping joint which is secured by fasteners and further made moisture impervious by application of a suitable sealant. Insulation can also be provided between the sheet metal roof skin and the decking.
Although the metal roofing system disclosed in the '100 patent significantly overcomes many of the problems of past metal roofing systems, several problems still remain. The metal roofing system disclosed in the '100 patent used fasteners that were spaced about one and a quarter inch from one another to secure the panels to the support members that were secured to the deck of a roof on a building or other type of structure. The fasteners typically were metal screws applied under high torque conditions to properly secure the metal panels to the support members. When the mechanical fasteners where applied to the metal panels under high torque conditions, the metal panels, typically formed of light gauge metal sheet material, were compressed by the fastener. As a result of the localized compression on the metal panels, the sealant between the overlapped edges of the metal panels was forced to ooze or be displaced out from between the panels adjacent to the location of the applied fastener; however, the overlapped region that was spaced from the fastener exhibited less compression thereby resulting in less sealant oozing from or being displaced from between the overlapping panels. Consequently, uneven compression of the sealant occurred between the overlapping metal panels during the installation of the metal roofing system. Such uneven compression resulted in a less aesthetically pleasing appearance of the roofing system due to the oozing of the sealant from between the overlapping metal roofing panels. As a result, additional installation time had to be taken to remove the sealant that had oozed from between the overlapping metal roofing panels thereby increasing installation time and driving up the cost of installation. The uneven compression of the sealant also increased the incidence that the watertight seal between the metal panel could fail or be compromised, especially during summer months when the metal panels can significantly expand and contract due to the large temperature changes that can occur throughout the day. In order to combat this problem, the '100 patent recommended that the spacing of the mechanical fasteners be about one and a quarter inch from one another. The close spacing of the mechanical fasteners was extremely labor intensive, resulting in a significant added cost to the installation of the metal roofing system. The spacing requirement of the mechanical fastener also led to installation error wherein uniform spacing of the mechanical fasteners was periodically not maintained, thereby resulting in the potential for forming an improper seal between the overlapping metal panels.
Another installation problem associated with the roofing system of the '100 patent was that the high torquing of the mechanical fasteners, when securing the metal panels, also resulted in periodic over torquing of the mechanical fastener which could result in damage to the metal panels. When the mechanical fastener was overtorqued, the head of the fastener could penetrate or puncture through the light gauged metal panels and/or be sheared off, thereby a) resulting in improper fastening of the metal panels to the support members, b) resulting in damage to the metal panels, and/or c) having an adverse effect on the aesthetics of the roofing system.
Still another installation problem associated with the roofing system of the '100 patent was the occurrence of fish-mouthing of the overlapping panels during installation. During installation, the installer had to stand adjacent to the overlapping panels so that the installer could apply a mechanical fastener through the panels and connect the panels to the underlying support member. The weight of the installer commonly caused the light gauge metal, that was supporting the weight of the installer, to slightly deflect. This slight deflection caused the edge of the metal panel to rise and commonly separate, thereby forming a wide gap in the overlapping region of the panels, commonly referred to as fish-mouthing. This wide gap occasionally resulted in the seal between the panels being broken, thereby compromising the watertight seal between the overlapping panels after the mechanical fasteners were applied to the metal panels. The deflection of the metal panel also resulted in potential bending of the metal panel, which bending could potentially adversely affect the orientation of the roofing panels when forming a complete roofing system and/or adversely affect the aesthetics of the roofing system. The raising of the edge of the metal roofing panel due to the deflection of the roofing panel also increased the difficulty in properly applying the fasteners through the overlapping metal panels and/or properly connecting the overlapping metal panels to the underlying support member. This increased difficulty increased installation time and cost and also potentially resulted in the improper fastening of the metal panels to the support member, thereby adversely affecting the life and watertightness of the roofing system. In order to minimize the problems with deflecting panels, installers commonly laid wood boards on the metal panels to distribute the installer's weight over the metal panels, thereby reducing the amount of deflection of the metal panel. Although the use of wood boards was effective in minimizing much of the deflection of the metal panels during installation, the installer had to periodically stop installation of the metal panels in order to reposition the wood boards, thereby resulting in increased installation time and installation costs.
Yet another installation problem associated with the roofing system of the '100 patent was that the metal panels tended to form a crease during the installation of the metal panels. The problem with creasing was more of a problem when the metal panels were corrugated. When the corrugated metal panels were fastened to the underlaying support members, the corrugation at the edge of the metal panels became slightly flattened, resulting in a fanning effect of the metal panel during installation. To counter the fanning effect, the installer commonly repositioned the panel. Such repositioning, if not done properly, resulted in the metal panel forming a crease in the overlapping panel region. Such a crease could a) adversely affect the seal between the overlapping panels, b) could increase the difficulty in properly connecting the overlapping panels in the creased region to the underlaying support members, and/or c) could adversely affect to the aesthetics of the roofing system.
Still yet another installation problem associated with the roofing system of the '100 patent was that when a mechanical fastener was inserted on or close to a metal seam on the metal roofing panel, the insertion of the mechanical fastener periodically caused one section of the metal panel to slightly raise, thereby damaging or compromising the integrity of the metal seam. When the mechanical fastener was fully inserted, the section of the metal panel that had been lifted was at least partially moved back into position; however, if the metal section was raised too much during the insertion of the mechanical fastener, the seam in the metal panel would not properly reform, thereby potentially resulting in a compromise to the watertightness of the seal and/or adversely affecting the aesthetics of the roofing system.
In view of the problems associated with the existing state of the art of metal roofing systems, there is a need for a metal roofing system that further decreases the time of installing the roofing system, further increases the ease of installing the roofing system, minimizes damage to the components of the roofing system during installation and, minimizes the occurrence of improper sealing of the roofing system components during installation.